1. Field of the Invention
The present invention relates to an electric-resistance-welded steel pipe with high strength for a door impact bar used for cars, and more particularly to an electric-resistance-welded steel pipe with high-strength for an impact bar used for the inside of an automobile.
1. Description of the Related Arts
In regard to doors for vehicles such as automobiles, a reinforcing material made of steel or the like is applied to the inside of a door to secure the safety of passengers in a car when another car crashes into the side of the car and to lighten the car weight. This reinforcement material is referred to as a door impact bar. Japanese Patent Application Laid Open No.197525/90 discloses a reinforcement material of a tube or a reinforcement material having a tensile strength of from 60 to 100 kgf/mm.sup.2 after stress relief annealing at a low temperature.
It is undesirable, however, to use the prior art reinforcement material as the door impact bar. The reinforcement material having a tensile strength of from 60 to 100 kgf/mm.sup.2 is insufficient for the door impact bar. Even though only this tensile strength is improved, properties effective for the door impact bar cannot be obtained.